Calculate Co2 For Indoor Gardens Using Co2 Tanks

CO2 benefits plants.

Plants use a complex process named photosynthesis to convert carbon dioxide (CO2) into sugar. For optimum growth and yield, plants require a tremendous amount of carbon dioxide. Plants are 90 percent water and 10 percent carbon. When other growth-influencing factors such as light, water and nutrients are in an ideal range, your indoor garden’s maximum crop yield is limited by the amount of CO2 it receives. If you increase the amount of CO2 in your indoor garden space, you will increase growth rate and crop production. That is why it is extremely important to have fresh air circulating in the garden room and to add CO2 supplementation. Does this Spark an idea?


1. Aim to get the CO2 levels in your indoor garden at 1,500 parts per million. This level sustains plants’ maximum growth and maximum yield. If your indoor garden is at the normal atmospheric CO2 level of about 300 parts per million, you’ll need to increase CO2 levels by 1,200 ppm, or .0012. (CO2 amounts vary by the season, but the base number of 300 ppm is used for growing room calculations.)

2. Calculate the amount of CO2 to add the garden room by multiplying the volume of your garden room by .0012. Measure the width, length and height of your growing room in feet. Determine the cubic feet of the room by multiplying those measurements. As an example, a 5 x 5 x 8-foot room contains 200 cubic square feet. Using the example of 200 cubic square feet, multiply 200 by .0012. Using this method of calculation, it will take .24 cubic feet of CO2 to bring the garden room up to 1,500 ppm.

3. Adjust the controls of your CO2 tank. CO2 tanks have a pressure regulator valve and a flow control valve. The pressure value is commonly preset between 50 and 100 psi. The flow control valve is adjustable. Increments are measured in cubic feet per hour (CFH).

4. Set the flow valve to the amount of cubic feet required to enrich the level of C02 in your growing room. In this example, the flow control would be set to .24 per hour. This setting will gradually raise the CO2 content of the room to 1,500 ppm. To reach the 1,500 ppm level takes approximately one hour.

5. Determine if your indoor gardening room is well sealed. Check that doors and windows are closed tightly. If air escapes under a door, put a towel under the door to block the airflow when you are adding CO2 to the growing room.

CO2 should not be used in an indoor garden room where you have to constantly run your exhaust to vent heat. CO2 should only be used in a well-sealed growing room. Otherwise, you’ll end up exhausting most of the CO2 out of your garden. CO2 tanks should be allowed to flow for at least three hours between exhaust cycles. Inexpensive CO2 monitoring kits are available for purchase online or from local greenhouses or gardening supply stores.